Here is the full list of all 99 Mist Legacy achievements.
Defeat Walkrock.
Defeat Ezhilya.
Defeat Tarathiel.
Defeat Rylenback.
Recruit Palenne Roirdan.
Defeat Hazko.
Defeat Whuzulm.
Build a first warehouse.
Defeat the Cybelfly Queen
Activate the Chimeric portal.
Recruit Badouk Brank.
Complete the Lithofortress.
Defeat Gularzob.
Be seefeets in Thorval.
Complete the adventures on the island of Tinylegs
Evolve Ovie.
Defeat the Great Protector.
Activate the Gantras portal.
Defeat Arriel and Ela.
Build a first dispensary.
Defeat Hilla
Evolve Finn.
Be recognized in Gantras.
Complete the Alchemy Learning Quests.
Be invited in Wellnear.
Become squire of the Protector of the Rose.
Activate the Norkantas portal.
Activate Thorval Portal.
Build a first workshop.
Be familiar in Larcen.
Build a first herbatum.
Become a Messenger of the Order of the Hippogriff.
Defeat Ilmagoth.
Activate Corinna's portal.
Complete the quests related to the Scabonzis.
Defeat the Scabonzi guardian protector.
Complete the collector Innkeeper quests.
Save Ouab and become a herbalist.
Defeat Rayth.
Defeat Valdiss.
Activate the Leviathan portal.
Integrate the guilds of Ordval for Leonidas.
Become an apprentice Arcanist.
Become a claw in the Assembly.
Investigate your first ruin with the druids.
Defeat Serassert.
Become acolyte of the Circle of the Great Tree.
Enter Giltanbourg.
Defeat Bobu.
Become a wanderer of the Lunar Caravan.
Defeat Hoboturla.
Pass the door of justice towards Gantras.
Reach the Fort of the Mistwalkers.
Activate the Wellnear portal.
Be recognized in Kortombe.
Activate the Enorwen portal.
Activate the Prettybard portal.
Recruit Corrin Fortvaillant.
Build a first shelter.
Learn the basics of magic with Yolasula.
Complete Sorka's quests.
Be accepted at Fearpiercing Camp.
Activate the Whisper Portal.
Recruit Finn Vorel.
Build a first barracks.
Build a first paddock.
Defeat Tortolus.
Defeat Zhyxhu.
Build your first cart.
Build an outdoor workshop.
Complete the Militia Introductory Quests.
Defeat the Aquagremfyr.
Learn to peer into the Mists.
Help all of the scribe's friends.
Activate the Kortombe portal.
Recruit Ovie.
Complete the tower construction quests.
Complete the introduction on the Troll Plateau.
Activate the Troll portal and come back to your domain.
Activate the Grandfall portal.
Build a first forge.
Build a first cutting plant.
Build a first sawmill.
Build a first tannery.
Build a first studio.
Become Mistwalker
Defeat heroic Whulzum.
Defeat heroic Gularzub.
Buy the flame frame.
Defeat heroic Hazko.
Defeat the Tarascarpel.
Defeat heroic Rylenback.
Defeat Eli'carde.
Defeat heroic Tarathiel
Defeat the army of darkness.
Defeat Cyclotus.
Defeat Mo'gul.
Defeat heroic Ezhilya.